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Elisabeth C. Miller Library

Archives: Plant Answer Line Q & A

Plant Answer Line questions and answers.

Artificially painted living plants

My alliums are done flowering, and the stalks look like straw. Can I spray-paint the flower heads now, or will it damage the plant below ground?

 

There are more natural and nontoxic ways of sustaining colorful garden interest. They involve planning and selecting plants that flower at different times throughout the year. Gardens are, of course, constructed landscapes and not the same as nature. Artificially colorizing spent plant matter appeals to some gardeners’ aesthetic sense but not to others. In my own garden, the alliums are done flowering but the nearby Eryngium (sea holly) is just taking off, dotting the bed with silver and blue. Some plants provide interest even when they are desiccated and brown through the winter, and I would include allium in this group.

However, if you would like to spray color on your allium heads, there are directions here that show how to make a kind of protective dropcloth out of a heavy paper plate with a notch cut into it.

It would be good to avoid getting any paint on the ground, and I suggest not doing it on a windy day. See if you can find spray paints that have lower volatile organic compounds. Despite marketing claims, there is no such thing as a non-toxic aerosol paint as this archived article claims.

There does seem to be a trend in marketing artificially painted living plants, such as succulents which are now being sold in big-box stores. This seems a pity, since there is such beauty in the actual shades of plant foliage. Additionally, this is short-sighted, because the plant will be unable to photosynthesize and transpire, and will eventually suffocate. See the following articles from Better Homes and Gardens, and Southern Living)

Another thought: if you want to cut the allium stalks and use less toxic water-soluble paints (such as casein) to paint them and display them indoors (where rain will not wash away the coloring), that is also an option. My personal preference is to appreciate the natural color of plants as they age and decay, but again, this an aesthetic choice—just like dyeing one’s hair.

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Mushroom identification

I was in the backyard tidying up after my dog when I noticed a tiny orange mushroom growing out of the moss in the lawn. It is a fragile thing, about an inch long. The cap has a slightly darker indentation on top. Even the stem is orange, and the gills look like the fan-vaulted ceiling of a miniature cathedral and extend a short distance down the stem. I am curious to know what it is.

 

I confirmed with local mushroom experts that this is Rickenella fibula. It is fairly common in the Pacific Northwest, but seldom noticed, so good spotting! The technical description of gills that extend down the stem would be “decurrent, slightly traveling down the stipe.” Here is general information about this mushroom from Michael Kuo’s Mushroom Expert site. He mentions that it may have a mutualistic relationship with moss, and that is discussed further on the Forest Floor Narrative blog:

“Most species that occur with moss are saprobes that share similar niche requirements with the moss. That is, many of these organisms can only exist in a certain range of temperature, moisture, pH, and nutrient content of the substrate. Much of the time, they don’t directly interact. Moss loving fungi break down dead plant material that may leach and be absorbed into the plant, but these interactions are not considered mycorrhizal. Recent studies indicate that Rickenella fibula doesn’t just coexist with the moss it is found growing with. There is actually a direct interaction going on here.”

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Colored bark mulch

We are planning to put down a seasonal mulch this spring and fall, and wondered what your opinion is of colored bark. Would brown, black, red, or some other color be best in our ornamental beds?

 

May I answer none of the above? There are better options. I can’t think of any good reason to apply mulches which have added dyes and colorants to any landscape. Check the Material Safety Data Sheets for each product to verify the source of the dye to be sure that they are not going to cause harm (to the landscape and the people and animals in it, and to stormwater). Some packaged colored mulches also have herbicides added, and I would highly recommend not using them. The sources of the “bark” may be an even more important cause for concern. This information from University of Massachusetts Extension points out that dyed bark mulch made from recycled treated wood can introduce toxic substances you would not want in your garden.

Although this is an aesthetic judgment call, to my eye, colored mulch always looks unnatural in the landscape compared to materials such as compost, leaf mulch, and arborist wood chips. Washington State University Extension professor of horticulture Linda Chalker-Scott is a strong advocate for the use of wood chips as mulch. My own observation is that bark mulch (in general, not just the colored bark products) often introduces weeds into a landscape. Chalker-Scott supports this observation in her book, The Informed Gardener (University of Washington Press, 2008):
“I have seen a number of landscaped sites where applied bark mulch immediately gave birth to horsetail seedlings.”

She further states that bark mulch from trees which have been kept in salt water can increase salt levels in your soil. Tree bark has a waxy covering, so bark mulch is not the best choice for absorbing and releasing water.

To summarize, unless you have your heart set on the look of dyed bark mulch, your garden beds would benefit from the alternative mulch materials (compost, leaf mulch, free arborist wood chips) mentioned above, plus planting an appealing and naturally colorful selection of ground cover plants in areas where that is possible.

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Growing kiwi

I have two very healthy kiwi vines, one male and one female. My female plant is flowering profusely right now, but there are no flowers on the male plant. I have had the plants for about 15 years or more and have never had fruit. They do not seem to bloom at the same time. I have just never bothered about it before, but this year I thought I would check out some options.

Any resources regarding hand pollination (both instructions and local suppliers) would be really helpful.

Oregon State University Extension’s guide, Growing Kiwifruit by Bernadine Strik (2005), has information about pollination:

“For fruit to be produced, male and female vines must be present in a block and must flower at the same time. Male flowers produce viable pollen for only the first 2 to 3 days after opening. However, female flowers are receptive to pollen for 7 to 9 days after opening, even when the petals have started falling.

“Pollination is extremely important in kiwifruit production. Large fruit contain 1,000 to 1,400 seeds (research on Hayward). If pollination is poor, fruit will have indentations (narrow valleys) on one side or be non-uniform in shape. If you cut through these fruit, you will find no seeds in these areas.

“Kiwifruit flowers are pollinated mainly by insects, although wind may play a minor role. Honey bees are the main pollinator used in kiwifruit vineyards. Kiwifruit flowers do not produce nectar and are relatively unattractive to bees. About three to four hives per acre are needed to adequately pollinate kiwifruit. Place these in the vineyard no sooner than 10 percent bloom of the female vines.

“In some years, you may have no male vines in flower as a result of winter injury to male plants (they are less hardy than the females). In this case, no naturally produced pollen will be available. To get a crop, the females will have to be pollinated artificially. Call your county Extension agent for more information on sources of pollen and methods of artificial pollination.”

(Note the section on Hardy Kiwi which are different than Fuzzy Kiwi.)

You might also find this article from The Olympian newspaper (May 16, 2009) of interest. It features kiwi growers Hildegard Hendrickson and ‘KiwiBob’ Glanzman, and discusses hand pollination, general care, pruning and training.

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Grass-carrying wasps

Who has moved into the tubes in my mason bee house? There are these strange bundles that seem to have dead crickets entombed in them. Do I need to remove them?

 

Your description and photos convince me that these bundles were made by grass-carrying wasps (Isodontia species) who store food (such as crickets!) with their cocoons to nourish the larvae when they emerge. Your mason bee house was a convenient location to nest. They look for any hollow cavities (such as stems, trees, or even window tracks), and the mason bee tubes were a perfect spot.

They would have built the nest in early summer, emerging later (late July through September) to visit flowers for pollen and nectar.

Grass-carrying wasps are beneficial insects just like mason bees, and serve as pollinators, too. This article from Heather Holm’s Restoring the Landscape with Native Plants (author of Bees: An Identification and Native Plant Forage Guide, 2017) mentions them visiting Solidago, Eupatorium, and Plantago.

As far as removing the grass-shrouded crickets or katydids, I would follow your normal mason bee housecleaning schedule. Usually, cleaning the tubes would be done between October and December. This page from David Suzuki’s web page describes the process.

If you are curious to see a grass-carrying wasp in action, entomologist Michael Raupp’s Bug of the Week page includes a video of a wasp creating its nest.

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Trees to attract hummingbirds

We have a dead cherry tree in front of our house. We’re sad that it died since birds loved it and it bloomed starting early winter. We’d like to find someone to replace it for us and we’d like the new tree to be small to medium in size and be a draw for hummingbirds and other birds as the old cherry tree was.

What tree would you recommend to replace our old cherry tree?

 

We recommend you select a certified arborist to remove the dead tree. There is a list online here where you can narrow a search to your area.

There are some evergreen, flowering shrubs which appeal to hummingbirds, such as Grevillea, which can reach 8 feet tall, depending on the variety. Arctostaphylos (Manzanita) species and Abelia grandiflora are also possibilities.

Trees which are attractive to hummingbirds (according to Welcoming Wildlife to the Garden, by Catherine Johnson and Susan McDiarmid, 2004) include Malus species (crabapple), Crataegus (hawthorn), and Sorbus sitchensis (Sitka mountain ash).

Here are some websites with more suggestions:
Backyard Wildlife Habitat
WA Dept. of Fish and Wildlife Backyard Wildlife Sanctuary
USDA National Resources Conservation Service’s Backyard Conservation tips

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Mystery trees of Tel Aviv

Sometimes reference librarians ask ourselves questions—especially in times of social isolation! Since libraries are closed, I have been rereading my own collection of books. When I Lived in Modern Times is a novel by Linda Grant, set in 1940s Tel Aviv before Israel became a state. The main character refers several times to unnamed trees that are growing along Rothschild Boulevard (Sderot Rothschild). The trees are noteworthy, yet she cannot identify them. After having read this book twenty years ago, I decided it was time to solve the mystery!

 

[mysterytrees] cover

By searching Google Maps, I could see there were two main types of trees. It’s a mile-long road with a central pedestrian thoroughfare, and in researching sources like Tel Aviv municipal archives and local news, I determined that both Delonix regia and Ficus (F. microcarpa and F. sycomorus) grow there. Delonix, native to Madagascar, was introduced to Israel in the 1920s and may have been planted on the boulevard then or later. The trees are depicted in a 1937 painting by Yehezkel Streichman, “The Kiosk on Rothschild Boulevard.” The ficus trees on Rothschild Boulevard were planted in the 1930s. Although jacaranda trees are mentioned in various historical sources, I did not see contemporary images of them, though a 1946 photo of Rothschild Boulevard at the intersection of Allenby Street (the very corner mentioned in Grant’s novel) shows jacaranda and ficus branches overhanging a photographer’s sidewalk photo-shoot.

Tel Aviv’s founders—with one exception—believed they could ‘make something from nothing’ (yesh me’ayin) of this sandy location. The lone dissenter thought it folly and, in a 1909 photo celebrating the city’s founding, he stands far apart from the others, atop a distant dune, possibly still muttering ‘crazy people, there’s no water here’ (meshuga’im—ayn kan mayim!).

Rothschild Boulevard was built in 1910, utilizing a sand-filled wadi (dry riverbed) which was not stable enough for buildings. The street’s original name was Rehov Ha’Am, Street of the Nation (or the People). Cypresses formed the outline of the boulevard’s edges, with grass and flowerbeds in the middle.

The city’s first mayor Meir Dizengoff had grand and somewhat impractical urban planning ideas. He wanted to impress Winston Churchill (who was due for a visit in 1921) by creating a tree-lined boulevard to rival any in Europe. Mature trees were transplanted from nearby locations, but they did not have time to establish themselves in the arid soil. When people thronged to see Churchill, some climbed the trees, toppling them. Churchill reportedly said, “That which has no roots is bound to wither,” a sly, barbed remark, coming from the man who was Secretary of State for the Colonies during the period of the British Mandate in Palestine.

In 1925, Patrick Geddes, a Scottish botanist and town planner, produced a plan for Tel Aviv. He envisioned a “garden city,” with a blend of “mainways” (for vehicles) and “homeways” (residential interior streets), and a series of east-west green boulevards to connect key urban sites, so the city would have a strong sense of nature.

To this day, Rothschild Boulevard is a well-used tree-lined corridor through the heart of a busy city. Just as we have cherry blossom mania in spring here in Seattle, there is great excitement when the red flowers of Delonix regia (known as flame tree, Royal Poinciana, Flamboyant, Gulmohar, and in Hebrew tze’elon naeh) bloom in early June. The ficus trees with their pale trunks sometimes covered in a net of accessory trunks made of aerial roots, are stately but drop fruit that can be perilous for pedestrians. Still, they are a notable feature of the landscape; Tel Aviv-Yafo municipal agronomist Haim Gavriel even published a recent monograph about the Ficus of Israel’s Boulevards.

Resources that were useful in researching this mystery include:

  • Mann, Barbara. A Place in History: Modernism, Tel Aviv, and the Creation of Jewish Urban Space. Stanford University Press, 2006. [accessed online 4/25/2020]
  • Mann, Barbara. “Tel Aviv’s Rothschild: When a boulevard becomes a monument.” Jewish Social Studies, New Series, Vol. 7, No. 2 (Winter, 2001), pp. 1-38. [accessed online 4/24/2020]
  • Rosenberg, Elissa. “Tel Aviv never stops.” Landscape Architecture Magazine 107 (11), 120-128
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Snowdrop buds won’t open

I planted some Galanthus ‘Flore Pleno’ three years ago. For all three years, the foliage comes up, buds form…..and then nothing. The buds swell and begin to color, but they never ‘drop,’ and will remain on the plants for up to two months without change. They never open, but very gradually become desiccated. They do not turn brown like daffodils with bud blast, and I see no signs of fungal disease. The foliage appears totally healthy. They are planted in a north facing bed, soil is medium-heavy but not waterlogged. I have done research but have found no explanation. Any thoughts are appreciated.

 

A general article by Christopher Lloyd on snowdrops in The Guardian (2001) makes a brief mention of heat causing bulbs to go blind (i.e., not flower), but this is said in the context of growing them indoors. Lloyd also mentions that Galanthus bulbs “are at their happiest in a clay/humus-rich soil that will be damp in winter and spring and dry during the summer.” They do not thrive in soil which is too rich or too acidic.

Another possibility is that you may need to divide them. Seattle’s Dunn Gardens has a helpful care sheet for growing snowdrops. Here is an excerpt:
“In the garden snowdrops do best in a partially shaded situation. If you have a very sandy, free-draining soil, amend it with compost. They love damp ground especially in the winter/spring. After the plant has finished flowering, allow the foliage to fully die down on its own. Do NOT cut the foliage off early, nor twist or braid it. Yes it will be ugly, but if planted around later emerging perennials, it won’t be so offensive.
“The Narcissus fly is the bane of snowdrops. After flowering, the fly will lay eggs on the foliage. The eggs hatch and the maggots will eat their way down into the bulb, destroying it. We’ve found that siting this bulb, where it gets afternoon or full shade after flowering, greatly reduces the chances of infestation. There is little in the way of chemical control, and what there is, is nasty.
“To bulk up galanthus, liquid feed after flowering, with a half strength solution of a water-soluble fertilizer, every two weeks, until the foliage has died down completely. If you
notice that the clumps are becoming congested (bulbs are starting to push up out of the ground), divide immediately after flowering.”

I recommend Naomi Slade’s book, The Plant Lover’s Guide to Snowdrops (Timber Press, 2014). In it, she describes in great detail the Fibonacci series by which snowdrops multiply: some varieties do this quickly, others slowly, in a mathematically governed sequence. The result of this natural system of propagation is that you will eventually have a dense clump of snowdrops that needs splitting up every few years if the bulbs are to have sufficient resources to produce flowers.

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Edible buckwheat and cushion buckwheat

What is the difference between the buckwheat plant that is used as an edible grain, and the wildflowers that are also called buckwheat? Are they related? I saw a plant growing on a ridge in the Olympic Mountains that was later identified for me as cushion buckwheat. Also, are there flowering buckwheats that people grow as ornamentals in gardens?

 

Edible buckwheat generally refers to Fagopyrum esculentum. If you were to find it growing wild in Washington State, it would be considered an escaped cultivated plant (i.e., weedy). It is sometimes grown as a cover crop, in addition to the use of its ground seeds for buckwheat flour. It is called a pseudograin or pseudocereal because it is not in the grass family (in the same way that amaranth, chia, and quinoa are pseudocereals).

Cushion buckwheat is Eriogonum ovalifolium. Like Fagopyrum, Eriogonum is in the knotweed family—Polygonaceae. There are about twenty native species of Eriogonum in Washington. Many of them grow east of the Cascades. Many more species of Eriogonum are native to California. (This article by Jennifer Jewell, Pacific Horticulture, April 2013 is a good introduction.) Many are best appreciated in the wild. If you want to grow buckwheat ornamentally, try to select a species that suits your garden conditions (ideally, in full sun, in soil that is well-drained and not overwatered, and mulched with gravel). Jewell’s article suggests that penstemon, salvia, and grasses might make good garden companions for the right species of Eriogonum. Plant expert Linda Cochran has experimented with growing a variety of Eriogonum umbellatum in her Olympic Peninsula garden.

Here is some interesting trivia about the scientific names for these different kinds of buckwheat, Eriogonum‘s name is derived from Greek: Erio = wool / gony = knee, referring to hairy nodes of the first scientifically described species E. tomentosum. Fagopyrum comes from Latin fagus (beech) and Greek pyrus (wheat) because the achenes (dried fruits) resemble beechnuts.

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On celandine confusion

Last year I purchased a plant at a plant sale. The tag said simply ‘celandine.’ It is flowering now, and its flowers are like yellow poppies. The leaves are attractive and very distinctive—deeply cut margins, kind of like oak leaves. But when I think of celandine, I think of the Cicely Barker flower fairies books from childhood. I am not sure this is the same plant.

 

You are not alone in experiencing ‘celandine confusion,’ discussed in this article from The Scott Arboretum of Swarthmore College. The confusion rests on the use of that common name to describe a plant that is a Washington State-listed Class B noxious weed in the buttercup family, and two different plants in the poppy family.

If you remember the illustration for “The Song of the Celandine Fairy” depicting ‘the lesser celandine,’ the illustration shows Ficaria verna (also called Ranunculus ficaria). There is also a ‘greater celandine’ fairy in Barker’s books, and that image looks more like Chelidonium majus which is in the poppy family and is a native of Europe. It is a bit harder to tell the difference between Chelidonium and Stylophorum diphyllum. Your plant is most likely one of these. Other common names for Stylophorum are ‘celandine poppy,’ and ‘wood poppy.’ Stylophorum is native to moist woodlands of eastern North America. Here’s what will help you tell one from the other:
According to Andrew Bunting, curator of the Scott Arboretum, “Stylophorum has broader leaves and Chelidonium leaves are more dissected. Also, the flowers are smaller on Chelidonium.” These images from Kathy Purdy’s Cold Climate Gardening blog neatly illustrates the differences in flower and leaf size. Further, when they reach the phase of producing seed pods, the difference is striking.

For additional information about Stylophorum, including suggestions of plant combinations for gardens, see this link from University of Wisconsin-Madison’s Master Gardener Program, and this one from Bruce Crawford, director of Rutgers Gardens, on the plant that launched his career in horticulture.

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